Martin Panter added the comment:
The most serious of these IMO is the signed overflow warnings in
Modules/cPickle.c. I get the same warnings if I disable the “gcc -fwrapv” mode:
/media/disk/home/proj/python/cpython/Modules/cPickle.c: In function
‘Unpickler_noload’:
/media/disk/home/proj/python/cpython/Modules/cPickle.c:5462:1: warning:
assuming signed overflow does not occur when assuming that (X - c) > X is
always false [-Wstrict-overflow]
Unpickler_noload(Unpicklerobject *self, PyObject *unused)
^
/media/disk/home/proj/python/cpython/Modules/cPickle.c:5462:1: warning:
assuming signed overflow does not occur when assuming that (X - c) > X is
always false [-Wstrict-overflow]
/media/disk/home/proj/python/cpython/Modules/cPickle.c:202:8: warning: assuming
signed overflow does not occur when assuming that (X - c) > X is always false
[-Wstrict-overflow]
if (clearto >= self->length) return 0;
^
/media/disk/home/proj/python/cpython/Modules/cPickle.c:202:8: warning: assuming
signed overflow does not occur when assuming that (X - c) > X is always false
[-Wstrict-overflow]
if (clearto >= self->length) return 0;
^
It is not clear to me where the overflows actually happen. See Issue 1608,
Issue 1621, where some of these bugs were fixed, and the “gcc -fwrapv”
workaround was enabled. Perhaps your compiler has a similar flag to use as a
workaround, though IMO it would be good to fix the code as well.
Most of the other warnings have been fixed or worked around in Python 3. I
propose to port the following revisions to Python 2. All but one are still in
effect today:
83a55ca935f0: Parser/pgen.c
12e53abec5d0, 0c7fff783b32: Include/objimpl.h
ce9f5ce33ad2: Modules/readline.c
a7a9e0f46b8a: Modules/tkappinit.c (change present in 3.3, 3.4, but eliminated
in 3.5)
e2f96bd29252 (partial): Modules/_ctypes/cfield.c
b04557ae099a (partial): Modules/expat/xmlparse.c (assuming this was the cause
of the ./pyconfig.h warnings)
That leaves the two warnings about CTYPES_CAPSULE_WCHAR_T. If necessary, they
could be worked around by adding an #if condition around the definitions:
#if defined(CTYPES_UNICODE) && !defined(HAVE_USABLE_WCHAR_T)
# define CTYPES_CAPSULE_WCHAR_T "_ctypes/[. . .].c wchar_t buffer from
unicode"
CTYPES_CAPSULE_INSTANTIATE_DESTRUCTOR(CTYPES_CAPSULE_WCHAR_T)
#endif
----------
nosy: +martin.panter
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